Please refrain from using vulgarity in the forums. I understand your frustrations however it doesn't help anything and only makes things worse.
Please give more details of how the 890L is configured when you have v1.11 loaded. is SC enabled? Test the router with SC disabled?
What devices are experiencing this supposed disconnects?
What are you doing when this disconnects are happening?
How many devices do you have connected at one time to the router?
Did you load the v1.11 FW manually as the process is seen here and
not load any saved configuration files afterwards? Link>
>FW Update ProcessAside the other users Roku 4 issue, v1.11 seems stable and works well for me. I don't have a roku 4 so I can't explain that fully. There maybe a wifi or SC driver compatibility issue there.
We need to know more information to see if we can help you more to figure out whats going on. If you feel the router is at fault then phone contact D-Link support and by all means, get an RMA unit in place while your under warranty for crist sake and see if a new unit resolves this or not.
Since your from the Sweden (EU) region, you should be loading what is the latest from this location:
http://www.dlink.com/se/sv/support/product/dir-890l-ac3200-ultra-wifi-routerThere maybe differences between the EU and NA regions which maybe causing problems. I recommend that you load what is available here. If you still seem to experience problems with the 890L, I recommend that you phone contact your regional D-Link support office and ask for help and information regarding this. We find that phone contact has better immediate results over using email.
I tried a 5300 last month...I sent it back is all I can say.